Field of the Invention
The invention relates to an apparatus for thermal ablation at a site in a subject. Particularly, the invention relates to an apparatus for treating uterine disorders by effecting necrosis of a uterine endometrium by use of a distendable bladder which is inserted into the uterus.
Brief Description of the Related Art
Application of thermal energy is known for treating body tissues and for causing necrosis. Particularly, it is well known to effect necrosis of the endometrium e.g. by use of an expandable bladder or a bladder which is filled with an inflation medium at an elevated temperature, herein referred to as necrosis temperature, typically about 80-90° Celsius.
In an unexpanded state, the bladder is inserted into uterus of the subject and a hot inflation medium is displaced into the bladder which thereby expands. Close contact between the hot outer surface of the bladder and the tissue lining for which necrosis is desired is maintained typically for 8-15 minutes after which the inflation medium is drained from the bladder. The collapsed bladder can finally be removed from the subject.
The inflation medium may be stored in a reservoir from which it can be displaced into the bladder. The reservoir can contain heating means for obtaining the necrosis temperature.
Under certain conditions, the bladder may expand prior to the treatment, e.g. in the bladder. Such an unwanted expansion may be due to handling, transport, or manufacturing conditions. Particularly, the bladder may expand due to thermal expansion of the inflation medium e.g. if the apparatus is stored in a warm place, or if the manufacturing process involves hot processes. If the bladder expands outside uterus prior to the treatment, it may become difficult or impossible to insert the bladder through the narrow cervix and the apparatus may potentially be unusable.